陕西省华阳川铀铌铅矿床碳酸岩岩石学及地球化学特征

摘要/Abstract

摘要：

陕西省华阳川铀铌铅矿床是小秦岭成矿带中成矿特征最为独特的矿床,碳酸岩脉的破碎带是重要的成矿空间。未矿化的碳酸岩中矿物以方解石为主,其他矿物很少;发育铀矿化的碳酸岩脉中矿物种类繁多,大部分为方解石,其次为角闪石、金云母、榍石、褐帘石、铌钛铀矿、重晶石、磷灰石、石英、磁铁矿、碱性长石等矿物。碳酸岩的LREE含量异常高,δ¹³C_V-PDB和δ¹⁸O_V-SMOW值显示典型的火成碳酸岩特征。基于碳酸岩脉的Sr、Nd、Pb同位素比值(⁸⁷Sr/⁸⁶Sr-²⁰⁶Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb-²⁰⁶Pb/²⁰⁴Pb-¹⁴³Nd/¹⁴⁴Nd-⁸⁷Sr/⁸⁶Sr)的关系图,初步判断华阳川铀铌铅碳酸岩脉是源于EMI的碱性硅酸盐-碳酸盐熔体-溶液结晶分异的产物。

关键词: 碳酸岩脉, 岩石学, 稀土元素, 同位素地球化学, 华阳川铀铌铅矿床, 陕西省

Abstract:

The Huayangchuan U-Nb-Pb deposit is a unique metallogenic type in the Xiaoqinling mineralization belt. The broken belt of carbonatite vein is important ore-forming space. The minerals in unmineralized carbonatites are mainly calcite, and there are few other minerals. Uranium mineralized carbonatites include a variety of minerals, major minerals of which are calcite; and minor minerals of which are amphibole, biotite,sphene,allanite,batafite,barite,apatite,quartz,magnetite,alkali feldspar. Carbonatites are characterized by high REE contents, whose δ¹³C_V-PDB and δ¹⁸O_V-SMOWvalues show the typical characteristics of igneous carbonatite. Based on the diagrams showing ⁸⁷Sr/⁸⁶Sr vs. ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb vs. ²⁰⁶Pb/²⁰⁴Pb and ¹⁴³Nd/¹⁴⁴Nd vs. ⁸⁷Sr/⁸⁶Sr of carbonatite veins, the authors consider that these carbonatite veins are crystal-fractionational products of alkaline silicate-carbonate melt-solution originated from the EMI.

Key words: carbonate vein, petrology, REE, isotopic geochemistry, Huayangchuan U-Nb-Pb deposit, Shaanxi Province

中图分类号:

P618
P588

惠小朝, 蔡煜琦, 何升, 冯张生. 陕西省华阳川铀铌铅矿床碳酸岩岩石学及地球化学特征[J]. 现代地质, 2017, 31(02): 246-257.

HUI Xiaochao, CAI Yuqi, HE Sheng, FENG Zhangsheng. Petrologic and Geochemical Characteristics of Carbonatites in Huayangchuan U-Nb-Pb Deposit, Shaanxi Province[J]. Geoscience, 2017, 31(02): 246-257.

图/表 20

参考文献 30

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矿物种类	方解石	黑云母	角闪石	碱性长石	石英	磷灰石	铌钛铀矿	磁铁矿	独居石	重晶石	榍石	褐帘石	其他矿物
矿化碳酸岩	55.19	15.52	5.78	6.69	0.28	0.28	0.79	0.28	0.55	3.50	0.90	0.24	10.00
矿化碳酸岩	62.34	15.97	6.58	0	0.50	0.18	0.37	0.30	0.27	3.16	0.23	0.14	9.96
未矿化碳酸岩	90.19	0.15	0.07	0	0	0.01	0.09	0	0.13	0.02	0	0.04	9.30

矿物种类	方解石	黑云母	角闪石	碱性长石	石英	磷灰石	铌钛铀矿	磁铁矿	独居石	重晶石	榍石	褐帘石	其他矿物
矿化碳酸岩	55.19	15.52	5.78	6.69	0.28	0.28	0.79	0.28	0.55	3.50	0.90	0.24	10.00
矿化碳酸岩	62.34	15.97	6.58	0	0.50	0.18	0.37	0.30	0.27	3.16	0.23	0.14	9.96
未矿化碳酸岩	90.19	0.15	0.07	0	0	0.01	0.09	0	0.13	0.02	0	0.04	9.30

矿物	Fe₂O₃	MgO	CaO	MnO	BaO	SrO	CO₂	H₂O	总量
方解石	0.77	0.47	51.76	1.52	0.22	1.02	42.48	0.08	98.32
方解石	0.62	0.24	52.61	1.23	0.21	1.06	42.71	0.30	98.98
方解石	0.39	0.15	56.05	1.63	0.13	1.01	41.11	0.1	100.57
方解石	0.45	0.33	54.44	0.59	0.22	1.11	42.65	0.07	99.43
平均值	0.56	0.30	53.72	1.24	0.20	1.05	42.24	0.14	99.43

矿物	Fe₂O₃	MgO	CaO	MnO	BaO	SrO	CO₂	H₂O	总量
方解石	0.77	0.47	51.76	1.52	0.22	1.02	42.48	0.08	98.32
方解石	0.62	0.24	52.61	1.23	0.21	1.06	42.71	0.30	98.98
方解石	0.39	0.15	56.05	1.63	0.13	1.01	41.11	0.1	100.57
方解石	0.45	0.33	54.44	0.59	0.22	1.11	42.65	0.07	99.43
平均值	0.56	0.30	53.72	1.24	0.20	1.05	42.24	0.14	99.43

矿物	Na₂O	F	K₂O	P₂O₅	MgO	SiO₂	CaO	TiO₂	Al₂O₃	FeO	MnO	总量
金云母	0.08	3.38	10.18	0.04	18.54	40.22	0.04	0.80	11.51	13.44	0.62	98.85
金云母	0.11	3.38	9.93	-	17.24	40.68	0.01	0.44	10.63	14.96	0.65	98.03
金云母	0.05	3.76	10.26	0.05	19.38	41.08	0.03	0.51	10.94	12.28	0.84	99.18
金云母	0.04	3.05	10.18	-	19.22	41.29	0.07	0.41	11.19	12.75	0.92	99.12
金云母	0.08	4.48	10.79	0.03	23.41	42.74	-	0.43	10.55	7.13	0.49	100.13
平均值	0.07	3.61	10.27	0.04	19.56	41.20	0.04	0.52	10.96	12.11	0.70	99.062